Fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, as described in U.S. Pat. Nos. 3,689,571 and 3,683,092, is an anesthetic which is showing very promising results in clinical trial, being non-inflammable under conditions of use, and having advantages that appear to greatly outweigh any minor disadvantage.
For clinical use, it is necessary of course to produce the above ether material in large quantities, for example, by a synthesis technique as described in the above patents, and the abandoned original application, Ser. No. 771,365 filed Oct. 28, 1978, from which the above-cited U.S. patents claim priority.
On scaled-up synthesis runs for the production of larger quantities of fluoromethyl-1,1,1,3,3,3-hexafluoroisopropyl ether, an undesirable fluorinated olefin byproduct has been detected in small quantities, for example, about 0.4 percent by weight. Since the ether material is intended for use as a clinical anesthetic, it is necessary to completely remove the olefin byproduct prior to administration to a patient.
The prime olefin byproduct produced with the ether material has a molecular weight of 314 by mass spectrometry, and has been tentatively identified as having a structure as follows (although the specific structure of the olefin impurity is not intended to limit the scope of this invention): CF.sub.3 C(CF.sub.3).dbd.CH--CH(CF.sub.3).sub.2.
The NMR spectrum obtained by us for the byproduct impurity corresponds to that reported by Yu. E. Aronov, et al. for the olefin product identified above (Izvestiya Akademii Nauk, SSSR, Seriga Khimicheskaya, No. 8, pp. 1758-1768 (1967).
The problem of the separation of this byproduct has been that it distills together with the ether, possibly as an azeotrope, which makes it essentially impracticable to separate the two materials by distillation.
In accordance with this invention, an effective technique for the removal of the fluorinated olefin byproduct is provided, as well as effective techniques for removal of the reactants used.
In the preferred instance, the reactant used is a physiological material which is easily removed from the product.